The extracellular acid protease produced by Rhizopus chinensis contains at least three different isoelectric forms. The amino acid sequence of the pI 5.15 form will be determined and a comparative study of the other isoelectric forms made to detect the differences in their structures. This information will be utilized to confirm or correct the tertiary structure solution by X ray diffraction performed by others. Contributions of various amino acid functional groups to the mechanism of action are being investigated. BIBLIOGRAPHIC REFERENCES: Delaney, R. Three molecular forms of Rhizopus chinensis acid protease. Abstract 37. Conference on Acid Proteases, Structure-Function and Biology. Univ. of. Okla. Nov. 21-24, 1976. Delaney, R. Relative effects of substrate binding and ion exchange on the binding of Rhizopus chinensis acid protease to poly-D-lysine agarose. Fed. Proc. 36, In Press (1977).